Spinal cord compression by an arachnoid cyst: a case report and review of the literature.

BACKGROUND: Intradural extramedullary cysts are a rare cause of spinal cord compression. We present a case with slowly progressive radicular pain and gait disorder over several years, due to medullary compression by a giant cervico-thoracic arachnoid cyst. CASE REPORT: A 65-year-old man presented with progressive pain irradiating from the lower back to the waist and both legs over a period of 2 years. Neurological examination revealed a decreased sensation for pain, vibration, and proprioception below T7, without muscle weakness. Reflexes were increased in both lower extremities, with bilateral extensor plantar responses. The MRI showed an intradural extramedullary lesion, suggestive for an arachnoid cyst. The spinal cord was displaced and compressed anteriorly, with a smallest diameter of 1 mm. Surgical resection of the cyst resulted in decompression and re-expansion of the spinal cord as visualized with MRI. Neurological examination 6 months after surgery revealed nearly complete recovery of neurological deficits. DISCUSSION: This case report, together with a review of the literature, shows the extreme adaptability of the human spinal cord, in cases of slowly progressive compression.